Tyrosine Supplementation does not Influence the Capacity to Perform Prolonged Exercise in a Warm Environment.

MedLine Citation:

PMID:
22805972
Owner:
NLM
Status:
Publisher

Abstract/OtherAbstract:

Eight males were recruited to a study designed to examine the effect of tyrosine supplementation on the capacity to perform prolonged exercise in a warm environment. Subjects entered the laboratory in the morning and remained seated for 1 h before cycling to exhaustion at 70% VO2 peak. Two 250 mL aliquots of a placebo or a tyrosine solution were ingested at 30 min intervals prior to exercise, with an additional 150 mL consumed every 15 min throughout exercise (total tyrosine dose: 150 mg/kg BM). Cognitive function was assessed prior to drink ingestion, at the end of the rest period and at exhaustion. Tyrosine ingestion had no effect on exercise capacity (placebo 61.4 ± 13.7 min; TYR 60.2 ± 15.4 min; P = 0.505). No differences in heart rate (P = 0.380), core temperature (P = 0.554), or weighted mean skin temperature (P = 0.167) were apparent between trials. Ingestion of tyrosine produced a marked increase in serum tyrosine concentrations (+236 ± 46μmol/L); P < 0.001) with this difference maintained throughout exercise. No change was apparent during the placebo trial (P = 0.924). Exercise caused an increase in error rate during the complex component of the Stroop test (P = 0.034), but this response was not influenced by the drink ingested. No other component of cognitive function was altered by the protocol (all P > 0.05). Ingestion of a tyrosine solution did not influence time to exhaustion or several aspects of cognitive function when exercise was undertaken in a warm environment.